List of fish that can live without oxygen

When choosing future residents for their home reservoir, many owners are concerned about the question of which fish live without air in an aquarium. In fact, fish, like all living things on the planet, need oxygen, which can be atmospheric or diluted in the water column. As for the air in the aquarium environment, there are phenotypes that can do without it.

What fish can live without oxygen

On the Internet, more and more people are trying to find the answer to the question, which fish can live without air? However, the answer does not quite suit them. It is impossible to find at least one living creature that can do without oxygen. But there are some aquarium inhabitants that can survive without a water aeration system.

The difference between fish is that some of them tolerate scarce water and can breathe atmospheric gas. Due to their ability, they are considered the most enduring and unpretentious to care for. There are several types of such inhabitants, but, unfortunately, not all were able to adapt to aquarium life:

  • Aquarium catfish or loaches. These fish use intestinal breathing with atmospheric air. It happens quite simply. Catfish rises to the surface, swallows air and sinks to the bottom.
  • Anabantoidei (labyrinth). They got their name because of the unique breathing apparatus, which is also called the branchial labyrinth. The air absorption process is similar to the previous one. The most popular aquarium representatives are: siamese fighting fish, gourami, dwarf gourami, macropods.

You should bear in mind that the absence of aeration and filtration entails an increase in the number of such manipulations as cleaning with a siphon, changing water, and conducting tests.

With the help of tests, you can find out the content of useful and harmful substances in the reservoir, for example, nitrogen that is harmful to fish.

In their natural environment, the inhabitants of stagnant water bodies, mainly in the subtropical zone, use skin respiration. The indicator of oxygen consumption through the skin in such fish reaches 80%, the standard figure is up to 20%.

Some fish can live and feel comfortable without aeration, but with good filtration.

If you have to maintain an artificial reservoir without filtration and aeration, then it is necessary to carefully select the species and breeds of fish, and combine the number of pets with the volume of the tank.

Spined loach

Cobitis taenia – distributed throughout Europe. It got its name from its characteristic spine in the gill area.

Before the weather changes, the fish begins to worry, swims actively, and more often captures air from the surface. In a calm state, the fish also breathes atmospheric air but rises to the surface less often.

Spined loach

The air is concentrated in the middle section of the intestine, and passing to the back section, enriches the blood with oxygen, through the small capillaries in the intestine. And because of that it is in the list of fish that can live without oxygen.

But intestinal respiration is about 20%, about 60% of oxygen is absorbed through the skin and another 20% falls on gill respiration.

These indicators are relative and depend on living conditions. Accordingly, if the water in the aquarium is poor in oxygen, then the loaches extract it from the atmosphere.

There is an assumption on the basis of which the family of loaches, having intestinal respiration, burrow in the substrate in order not to rise to the surface of the water. The swallowed air bubble in the intestines lifts them, so drifting loaches float to the surface.


  • a reservoir with a volume of 10 liters is suitable for breeding;
  • no sharp decorations;
  • use coarse and fine soil;
  • temperature range from 3 to 30 degrees;
  • food is standard. Give it something and loach will show what it likes.
  • harmless fish, prefers the same neighbors.

Kuhli loach

A loach fish looks like a mini-snake or a large yellow worm with a black stripe. The family is carp. The preferred temperature is around 25 ° C.

It uses atmospheric air as oxygen enrichment, which passes through the intestines. In addition, kuhli loach are able to absorb oxygen through the skin. To carry out the skin respiration of this fish, there must be oxygen in the water.

Kuhli loach

For oxygen enrichment, an aerator is not necessary; a device such as a flute that works through an internal filter pump is suitable.

But just a filter is also suitable, the release of which is directed to the surface. Thanks to this filtration mechanism, the water will be enriched with oxygen.

The loach Kuhli deserves a caregiving effort. Striped snake like pets are distinguished by a peaceful disposition and a passion for solitude.

But they know how to stand up for themselves. They have a sharp thorn under the eye. It is convenient for it to pave the way in sand, soft ground. An irreplaceable defensive weapon. Sometimes piercing predators intestine, sometimes ripping open the stomach.

Conditions of keeping:

  • feel comfortable in small ponds;
  • it is necessary to provide shelters in the form of snags, stones, castles;
  • they do not need a special diet – microorganisms from the soil are suitable, waste from the rest of the population. Indulge in live, frozen treats;
  • can jump out – a cover is required;
  • difficult breeding, subject to a professional;
  • get along with almost everyone.

Paradise fish

Paradise fish are endurant species.

They are not demanding to the temperature and feel equally comfortable both at + 16 ° С and + 25 ° С.

Paradise fish

Very fertile and live very long. Resistant to cloudy water, cold. They are pugnacious, do not tolerate small neighbors. The worst temper is among the black representatives. The king of reservoirs – one of the first types of European aquarium hobby.

Filtration is considered mandatory. Experience shows that this is not the case.

Easy to breed in aquariums.
More about the habitat:

  • do not grow even in a 300-liter fish tank;
  • omnivorous – plant, protein food is suitable;
  • Usually, people use coarse sand, expanded clay, small pebbles as a soil. Narrow decorative shelters will not work – paradise fish cannot move backward, they will get stuck, and die.
  • it is advisable to add plants covering the surface of the water (Duckweeds);
  • a cover is required that does not block access to atmospheric air;
  • average illumination level;
  • not recommended for a shared aquarium with small defenseless fish.


Fish from the order of Perciformes, with a labyrinth organ. It is thanks to the structure of this apparatus that gourami extracts air and provide themselves with oxygen.

A prerequisite in an aquarium is unhindered access to atmospheric air. In their natural environment, gourami were found in sewers, small, “stagnant” bodies of water, where water with low oxygen levels.


Gourami and other labyrinth fish need access to atmospheric air, and during transportation, oxygen pumped into the bag can destroy the fish, since it burns the respiratory organs of such a (labyrinth) structure.

Kissing, pearl, marble, gold, spotted are the most popular species. It’s not worth checking, but they can live up to 6 – 8 hours without water. Friendly, curious, playful.

 Recommendations for gourami:

  • the length of the aquarium is at least half a meter;
  • volume from 50 liters;
  • breed in floating plants;
  • shelters are required, space for free movement, games;
  • dark soil emphasizes the beauty, colorful, bright color of fidgets;
  • not picky about food. The menu should be varied. Delight them with herbal, dry, lively dishes. Overfeeding is not recommended.
  • Will make friends with dwarf gourami, other peaceful labyrinths, loaches.

Dwarf gourami (lalius)

Yes, dwarf gourami too goest to the List of fish that can live without oxygen. They are shy. Stay in flocks of three individuals to feel more confident. They live for about 2-3 years.

This is a small, bright fish, with a labyrinth respiratory apparatus, belonging to the family of gourami.

Dwarf gourami (lalius)

Does not require special care, food and maintenance are not whimsical. If a filter is installed in the aquarium, dwarf gourami will feel more comfortable.

The aquarium cover will prevent the inhabitants from jumping out of the aquarium. And if the lighting is built into the lid, then the plants will grow more actively, and therefore create an additional diet for the fish and a favorable microenvironment.

The following conditions are comfortable:

  • aquarium volume from 15 – 20 liters;
  • for spawning, thickets of plants are needed in the corners of the reservoir;
  • do not belong to gourmets, but monotony in feeding is destructive. Balance protein with plant foods;
  • prefer calm, non-aggressive neighbors, such as guppies.

Siamese fighting fish

The most popular representative of the list of fish that can live without oxygen. Under good conditions, these fish live up to 3-4 years. They are not demanding to care, but cleanliness must still be observed. 3 liters is enough for one fish.

Betta splendens absorbs atmospheric air, floating from time to time to the surface, captures an air bubble from which it produces oxygen.

Siamese fighting fish

Siamese fighting fish are often chosen as one pet in an aquarium. But driftwood, algae, grottoes, lighting will make the it’s life more joyful.

The water change should be carried out as with other fish species:

  • at least once a week, in containers from 10 to 20 liters.,
  • if the aquarium is up to 5 liters, then add fresh water 2 times a week.

The siamese fighting fish lives a little, but brightly.
Aggressive bullies are ready to destroy a weak, small, clumsy relative.

Required minimum:

  • for one fish 5-10 liters of liquid;
  • live, artificial plants, decorative items are necessary for breeding and shelter from an aggressive male;
  • use on them various food but they are not picky. Special mixes for betta fish are on sale;
  • do not get along with labyrinths.

Thick-lipped gourami (labiosa)

This representative of the labyrinth is often mistakenly referred to as gourami, calling them honey. Nevertheless, this fish is called labiosa of the genus Trichogaster (until 2017, the genus Colisa).

The similarity with gourami is very strong, both externally and in conditions of detention. But they usually grow larger, up to 9 cm.

Colisa labiosa (thick-lipped gourami)
Labioses do not need an aerator, as they process the air with a labyrinth apparatus, extracting oxygen from the atmosphere. Given this feature, the fish often lives in the upper layers.

The aquarium, which contains labiosa, must be equipped with a “cover”, that is, close the top in order to prevent them from jumping out of the “house”.

It is believed that the cover is also needed to maintain the microclimate above the water so that the fish does not catch a cold while absorbing oxygen.

Thick-lipped gourami are large quiet ones. The male’s purple color indicates his arousal. Suitable for multi-species breeding.

About the conditions of detention:

  • 10 liters of water per representative;
  • love algae (Echinodorus, Waterweeds, Cryptocoryne);
  • special attention to water temperature (+ 25 … + 28 degrees);
  • a small variety of food is suitable;
  • like many peace-loving fish can not tolerate restless aggressors.

However, do not expect that these animals can live completely without air. They need it, so in no case should they block access to the air from above.


Popular fish for aquarium lovers and has special place in the list of fish that can live without oxygen. There is an opinion that catfish do not need air, but this is not entirely true.


There are species that absorb oxygen from the atmosphere, and there are catfish that do not need high oxygen enrichment. For example, corydoras paleatus have intestinal respiration, extracting oxygen from the atmospheric air.

Ancistrus, Pterygoplichthys, and other L-catfish require good oxygen enrichment, while thoracata and otoncyclus can get by with a small amount of H2O.

Catfish live in the lower layers of water bodies. Constantly cruising along the bottom and turning the soil, they raise the dregs from the bottom. A filter pump in an aquarium with catfish will provide not only filtration but also enrichment of water with oxygen.



Guppies are one of the most common aquarium fish. They are distinguished by the simplicity of care, unpretentiousness, perky character, and an abundance of colors. The homeland of these fish is the flowing water bodies of Central and South America. Nowadays, guppies are common on almost all continents. Fish in nature are very different from modern breeding forms: wild guppies are less colorful and bright, and they live longer than in an aquarium, about 3-4 years.

The size of the fish is small: males grow about 3-4 cm, females about 5-6 cm. Males are famous for their luxurious veiled tails. However, there are varieties of guppies with modest tails – forks. The color of the guppy can be either one color, for example, yellow, or multi-colored, for example, a blue cobra.

They don’t need much oxygen and can live in a small fish bowl.

Signs of a lack of oxygen:

  • Fish rise to the upper layers;
  • After a couple of hours, the fish protrude their gills;
  • Decreased appetite;
  • The immune system suffers;
  • Growth slows down or death occurs in 2-4 days.

Death may not occur, but the fish experience constant discomfort, and all life processes will pass slower, which affects the growth, color and behavior of the animal.

Thus, fish cannot live completely without oxygen, however, you can make your life easier by buying inhabitants that can breathe atmospheric air using our list of fish that can live without oxygen. But even with a small choice, you can collect the best representatives and create a unique reservoir where fish and catfish can live without discomfort.

Labyrinth organ

The labyrinth is a specialized respiratory organ that allows you to absorb oxygen directly from the air. Labyrinth fish take the air “swallowing” it from the surface of the water. Therefore, such fish do not need aquarium aeration! However, if access to the surface of the water is closed, such a fish will soon die.

Signs by which it is determined that the fish need more oxygen

If the fish often begin to take air from the surface of the water, even those that spend most of their lives in the lower layers of the aquarium, then this is an alarming signal. They really need oxygen dissolved in water. What measures should be taken in this case?

First, measure the water for ammonia, nitrite, and nitrate. If the amount of harmful impurities is increased, replace 40-50% of water with clean, fresh, and acceptable parameters. Do not pour out all the water, it is detrimental to the life of pets. If the indicators of ammonia and nitrates, nitrites are normal, then increase aeration and add an air pump to the water.

Air pumps – what are they for and to whom?

Air pumps are commonly used in water filtration systems, there are different types of such stones, in different shapes and sizes. They help the fish that breathe with the labyrinth organ and saturate the water with additional oxygen. Small air stones float on the surface of the water thanks to their lightweight and floating composition. Heavy air stones can be placed against the back of the aquarium for additional decoration.


Most labyrinth fish do not pose any particular problems in their keeping. The volume of their place of residence does not play a particularly important role. Like fish that do not need oxygen, they assume some conditions for their keeping:

  • The aquarium water temperature should be 24-27 ° C.
  • The substrate used should preferably be of dark color – this enhances the coloration of the labyrinth fish, which emphasizes their beauty.
  • For females of this family, dense vegetation is needed so that there is where to hide from aggressive males.
  • Labyrinth fish are not particularly picky about food and willingly eat both live food and dry or frozen. If you want to know what to feed fish check this article.

Keeping them together with representatives of another or their own species of fish is often problematic. Many adults (most often males) show aggression towards fish that represent their species. This happens especially often when the volume of the aquarium is small.

In order for the aquarium to have peace and quiet, the water must be “old”; changing water provokes the reproductive instinct and causes aggression.

Fish that do not need oxygen generally require access to ambient air. To prevent the fish from jumping out, it is good to cover the aquarium with a lid. There must be at least 5 cm between the lid and the water surface.